Printing device and recording paper control

ABSTRACT

A printing device and control method that facilitates setting of waiting periods for cut-sheet paper insertion and commencement of paper transport or printing through application of waiting time control commands. By establishing a command for setting these waiting periods and incorporating apparatus in the printer for analyzing such a command, a configuration is realized in which these waiting periods are settable and adjustable by the host computer. This provides more efficient POS type printer control and allows setting of the desired time required for positioning recording paper according to operator experience. An interface unit is used to receive and interpret print data and recording paper positioning time setting commands and data from the host computer. The received commands and data are temporarily stored in a data memory, and after insertion of the recording paper is detected, used by one or more timing circuits to wait for a set amount of time before transport of or printing on the cut-sheet paper is initiated by a printing mechanism controller, during which time paper positioning is confirmed.

This is a continuation of copending application Ser. No. 07/902,318filed Jun. 22, 1992.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to printing devices operating inconjunction with host computers and more particularly to printersconnected to a host computer that provide output in response to commandsfrom the host computer. The invention further relates to point-of-saletype printers capable of printing on cut-sheet type paper.

2. Related Technology

A variety of small specialized printers have been developed and widelyused with host computers and other apparatus for printing dataassociated with point-of-sale (POS) transactions. A common example ofsuch a printer application is for a department store where such printersare used to generate a "tape" style purchase receipt on "recordingpaper" for a customer which lists the items purchased as well as taxesand other fees levied against the transaction and a total balance due.These printers are used as part of the so called cash or check-out"register" commonly seen throughout retail business. In addition to therecording paper, these printers are also generally required to generatea "journal" or "journal tape" on a roll of paper for permanentlyrecording and verifying the transactions for the particular salesregister.

The printing devices used for these kinds of transactions generallytransported a recording paper material, typically from a roll of paper,along a preset paper path through a printing mechanism where a printhead forms the output image. More recently, due to the nature of recordkeeping and the sales transactions themselves, single or "cut-sheet"paper has found use in sales transactions. Additional information,business logos, instructions, or terms and conditions of the sale arenow included as part of the transaction receipt, or specializedtransaction forms, such as for "credit" transactions, are used.Therefore, many POS printers are configured with an insertion or accessslot to provide access for insertion of individual cut-sheet paper orforms into the paper path for the printing mechanism.

In any case, POS printers are currently configured to begin printingimmediately, when a switch is activated by an operator, or within a setelapsed time after it is determined that paper has been inserted intothe mechanism, particularly cut-sheet paper. Since the time it takes toposition recording paper in POS printers, and the like, varies accordingto operator skill or experience, this currently gives rise to twoinefficient conditions. First, an operator may be required to wait untilthe end of an allotted elapsed time interval even after the recordingpaper is positioned within the printer. Second, once the recording paperis detected, regardless of whether or not correctly positioned, it istransported into or through the printer before being correctlypositioned, often causing problems.

On the other hand, if a maximum waiting time for insertion of recordingpaper is not set, the host computer will wait indefinitely until itreceives information from the printing device regarding insertion of therecording paper, also resulting in lost time. At the same time, if anoperator mistakenly sets the printer in a cut-sheet paper printing mode,it is sometimes necessary to turn off the power to the printer to escapethis mode, which also resets other settings.

What is needed is a method and apparatus for setting and changingwaiting times for paper insertion, positioning, and transport which canflexibly account for the skill of the operator. Something is needed tooptimize the allocation of time for POS paper insertion activities whilefacilitating host control through application of new transport controlcommands.

SUMMARY

In order to solve these and other problems, one purpose of the presentinvention is to provide a printing device that optimizes the waitinginterval for recording paper insertion;

Another purpose is to facilitate user control of the cut-sheet paperwaiting time by means of control a command.

Yet another purpose of the invention is to allow the time intervalbetween recording paper insertion and transport to be selectively set,generally using host computer commands.

An advantage of the present invention is that it optimizes recordingpaper control in a printing device.

Another advantage of the present invention is that it realizes efficientdata transfer and optimization of commands by facilitating setting ofthe recording paper insertion wait time and the recording paperpositioning time with the same command.

These and other purposes, objects, and advantages are realized in aprinting device having a printing section with a printer head forprinting on cut-sheet and other types of recording paper, and a papertransport mechanism for moving paper adjacent to and past the print headin the printing section. A paper detector is used to detect whenrecording paper is inserted in the printing device and a timing unitconnected to the detector and transport mechanism is used to start papertransport when a first predetermined time interval for positioning ofrecording paper has elapsed after detection of the paper. A positioningor position control element is used to variably set a desired first timeinterval. In the preferred embodiment, the printing device also uses aninsertion or insertion control element to variably set a second timeinterval as a maximum wait time for recording paper insertion. A warningor error detection unit produces an error signal if no recording paperis detected within the second time interval.

In further aspects of the invention, the timing element uses at least afirst and second timers to count the first and second time intervals,respectively. An interface unit is connected to a host computer toreceive commands from a set of predefined commands, print data, andother data strings. A data analyzer interprets or decodes the receiveddata and commands, at least one of which is at least one time settingcommand for setting the length of at least the first time interval, andgenerally also setting the length of time for the second interval.Preferably a single command is used to set the first and second timeintervals, and it typically comprises a two-byte length commandparameter set with one byte used as a command parameter indicating thefirst time interval and the second byte used as a command parameterindicating the second time interval.

A data storage or memory element is used for storing analyzed data whichindicates at least the first time interval as specified by the timesetting command and provides this data to the timers for measuring thespecified time periods. A print controller activates the first of thetwo timers after recording paper is detected, confirms the detection ofthe recording paper and paper position, and initiates paper transportand printing.

The paper transport mechanism has a transport section open-closemechanism configured to be electrically operated to open and close arecording paper transfer path and a recording paper transport roller,and a recording paper transport controller to confirm the positioning ofthe recording paper, and then operates the transport section open-closemechanism, holding the recording paper so that it can be transported,and driving the recording paper transport roller.

The data storage or memory is configured as a first memory unit in whichdata, command parameters, defining the first time interval as specifiedby the time setting command is stored, and a second memory unit in whichdata defining the second time interval is stored. The first and secondtimers use the data from the first and second memory units to measureelapsed times for paper positioning after insertion before commencingprinting or transport, and for waiting insertion. A first activationelement starts the second timer after waiting for recording paperinsertion and confirms whether or not the recording paper was insertedwithin the specified wait time, and a second activation element startsthe first timer so as to measure the elapsed recording paper positioningtime. A timer controller having a calculation element can be used tocalculate elapsed times for at least the first time interval based onstored parameters and detector output. A confirmation element checkswhether or not recording paper has been inserted within the calculatedwait time.

The method of operation includes selecting a length of at least thefirst time interval for paper positioning, detecting the presence orabsence of paper inserted in the printing device, measuring the firsttime interval beginning with detection of paper, and initiating papertransport through the printing section after passage of the timeinterval, provided paper has been detected. In further embodiments, thelength of the second time interval defining a maximum time periodallowed for paper insertion in selected and an error signal is producedwhen no paper is detected within said second time interval.

Using the invention, it is possible to set both a waiting time forinsertion of paper and a desired time interval between when therecording paper is detected until transport commences, thus facilitatingselection of the recording paper positioning time according to the skillof printer device operators in the POS field. Furthermore, wheremultiple cash registers are connected to a host computer, the recordingpaper positioning time can be set in advance for each individual cashregister.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention may be better understood from areview of the following description when taken in conjunction with theaccompanying drawings, in which like numbers refer to like parts and inwhich:

FIG. 1 illustrates a function block diagram of one embodiment of thepresent invention;

FIG. 2 illustrates a flowchart of the recording paper positioningprocess used for the invention;

FIG. 3 illustrates a block diagram of a control circuit for a printingdevice mechanism constructed and operating according to the principlesof the invention;

FIG. 4 illustrates a simplified diagram of one embodiment of theprinting device mechanism of the invention;

FIG. 5 illustrates a flowchart of the overall process followed by thecontrol method of the present invention; and

FIG. 6 illustrates an embodiment of the command structure used toimplement the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention provides a method and apparatus for controllingselection of waiting time or intervals for recording paper insertion andpositioning within a printing device. The printing device is configuredto respond to commands and data from a host computer and allow selectivecontrol over these intervals for optimizing performance according tooperator experience and other factors.

A simplified cross section of one embodiment of the mechanical portionof a printing device constructed and operating according to theprinciples of the invention is illustrated in FIG. 4. Additionaldescriptions of this type of printing device are also found inco-pending U.S. patent application Ser. No. 07/507,319 owned by the sameassignee, and incorporated herein by reference. This embodiment has amechanism capable of printing on at least two types of recording paper,i.e., roll paper and cut-sheet paper. Cut-sheet paper is indicated inFIG. 4 by the numeral designation 170 and roll paper is indicated by171.

In FIG. 4, the mechanical portion of a printing device is shown using aprint head 1 having print wire pins 1A (only one shown), and an inkribbon 1B. A platen 2 is mounted opposite print wire pins 1A on asupport or support frame 5 so that it is movable back and forth alongthe directions indicated by arrows A and B. This movement isaccomplished by pivoting support 5 about a shaft 5A using a plunger 15connected to the support. A recording paper drive roller 3 and anopposing auxiliary roller 4, which is positioned on the support 5, arepressed together to provide friction feeding pressure on recording paper170 disposed between the rollers. Plunger 15 and support member 5 formthe principal constituent parts of a printing section open-close orengage-disengage mechanism, which opens and closes over the paper asappropriate. Along with drive and auxiliary rollers 3 and 4,respectively, this structure also constitutes a recording papertransport section 20 for the printing device.

A recording paper drive roller 8, in conjunction with an auxiliaryroller 9 pressed against it, is also used for transporting recordingpaper 170. Auxiliary roller 9 is positioned so that it is supported by asupport arm 10 and can be rotated along the direction of arrow C bybeing pivoted on a pivot point 10A by a plunger 16. Plunger 16,auxiliary roller 9, and support arm 10 form the principal components ofa transport section open-close or engage-disengage mechanism, which inconjunction with drive and auxiliary rollers 8 and 9, constitutes arecording paper transport section 30. A recording paper guide plate 11establishes an upper paper transport path 13 for recording paper 170adjacent to print head 1.

Cut-sheet paper is generally divided into standard size validation cardsand "slip paper" which can be easily copied or duplicated. A frame notch12 is typically positioned along the periphery of validation cards forpositioning, and generally has a structure that allows lateralinsertion, from the side of printing devices, for standard sized cards.

Also shown in FIG. 4, is a type of photosensor 6, having an optical axis6a, for the recording paper detection element that detects insertion ofrecording paper, and a stop element or stopper 7 for assisting in theguiding and alignment of cut-sheet paper during insertion. Stop 7 islinked to plunger 16 and is disposed along a lower paper path 22 so thatit is movable across the paper path to selectively block or open andclose the recording paper path.

Cut-sheet paper 170 is inserted from or along the direction indicated byarrow 22A and is considered positioned in recording paper path 22 whenit strikes against stop 7. The presence of recording paper 170 in thisposition is detected by the fact it crosses or blocks optical axis 6A ofphotosensor 6, thus changing the amplitude of light received by adetector. When paper is detected, plunger 16 is retracted moving supportarm 10 about pivot 10A, which closes recording paper transport section30, and presses rollers 8 and 9 against opposite sides of recordingpaper 170. At this point, stop 7 is also moved out of recording paperpath 22, typically using a series of lever arms or gears connected toplunger 16, which opens the recording paper path allowing recordingpaper 170 to be transported to a printing position by drive andauxiliary rollers 8 and 9. When recording paper 170 is transported tothe printing position, plunger 15 is retracted to facilitate furtherrecording paper transport by the drive and auxiliary rollers 3 and 4.

The cut-sheet paper is positioned by correctly pushing it against stop7, when it is in the "pull-in" position across paper path 22. Thisallows accurate transport of the recording paper. As previouslymentioned, the time it takes to correctly position the recording paperdiffers among printing device operators according to their relativelevel of experience, among other factors, and there are cases in whichproblems arise if recording paper transport is begun immediately afterinsertion is detected. Therefore, the preferred embodiment of thepresent invention controls the printing device as described below.

As an alternative to cut-sheet paper, a roll paper holder 41 holds rollpaper 171, as seen in FIG. 4, which is ejected from the printingmechanism along the direction indicated by arrow 41B and dotted line41A.

A block diagram of an exemplary controller found useful for controllingthe printing device mechanism described above is presented in FIG. 3. InFIG. 3, a printing device mechanism 100 is shown using a print head 101,plungers 102 and 103, which correspond to 15 and 16 above, a motor 104that serves as the drive source for recording paper transport, and arecording paper detector 105. A central processing unit (CPU) 60performs general control of the entire printing device using a ROM 61 tostore programs or instructions, etc., that analyze and execute alldevice and control commands sent from the host computer and are used aspart of the control method for the invention. In addition, a RAM 62 isalso connected to CPU 60 for temporarily storing data, along with atimer 63 for measuring certain prescribed time periods, and an interfaceor control command receiver 64 for receiving input print data andcommands from the host computer.

Central processing unit 60 uses an I/O port 70 for communicating withvarious elements in the printing device which it is controlling.Exemplary elements connected to CPU 60 I/O port 70 include a print headcontroller 71, plunger controllers 72 and 73, a :motor controller 74,and a recording paper detection circuit 75. Detection circuit 75 is alsoconnected to recording paper detector 105, which detects the presence orabsence of recording paper in the transport path.

CPU 60 receives data from or through interface 64, and while analyzingthis data, controls printing device mechanism 100 based on that data sothat prescribed printing operations are executed. That is, CPU 60prepares printer data, generally the letters and numbers to be printed,by interpreting input data and separates out commands from the printdata.

Functional operations for the invention are illustrated in the blockdiagram of FIG. 1. In FIG. 1, data transferred to input interface 64 isanalyzed or interpreted by a data analyzer 151 and the results stored ina preselected area or address range in RAM 62, acting as a transientmemory unit, using a data storage controller 150. If time settingcommands for either a cut-sheet paper positioning period or interval, ora recording paper insertion wait interval are contained in the inputdata, the interpreted interval values are also temporarily stored in RAM62. When the input data contains print data, such as characters ornumbers, which are to be printed on cut-sheet paper, in response toprint commands, then the printer, or CPU 60, waits for insertion ofrecording paper before printing is commenced.

However, if a maximum time interval for waiting for recording paperinsertion is set at this point by a time setting command, then theprescribed parameters or limits for this time interval are retrieved orread out by data storage controller 150 and converted to time data, thatis, start and stop times etc., by a timer controller 140 which generallyincludes a calculation element. A timer 152, referred to as a "second"timer because of its relationship to the printing sequence, is thenactivated and set to count an "insertion wait" time interval based onthis data. A recording paper detector or detection unit 153 waits for,or seeks to detect, insertion of the recording paper while second timer152 is activated and counting. When insertion of recording paper isdetected, a first timer 154 retrieves or recalls positioning wait timeinterval data previously set by the paper positioning time settingcommand from data storage. This data is also converted to time data bytimer controller 140, and then used to set prescribed time interval tobe measured by timer 154.

Timer 152 measures the waiting time set by the host computer forcut-sheet paper insertion while timer 154 measures paper positioningwait time or pause interval set for starting operation after paperinsertion. The parameters for these intervals are provided by the hostcomputer, unless a default value is used, and stored in RAM 62, alongwith other data as required, until needed. A timer or timing circuitsbuilt into CPU 60 is generally used for implementing the timers, whichcan include the application of software timers as desired.

A recording paper positioning confirmation unit 155 confirms whether ornot recording paper is correctly positioned after the preselected paperpositioning time interval has elapsed, and if so printing control istransferred to printing mechanism controller 156. Printing mechanismcontroller 156 comprises a recording paper transport section open-closemechanism 157, recording paper transportor 158, and a printingcontroller 159, which act to sequentially transport and print data oncut-sheet paper 170. Otherwise, if no recording paper is detected aftera time interval selected by second timer 152 elapses, then a warningindicator, light, buzzer, or similar annunciation or attention seekingelement is activated or generated by error processor 160 to indicate arecording paper positioning error to a printing device operator. At thesame time, the error can be recorded as error detection data in memoryalong with operator identification or other relevant information totrack historical efficiency patterns.

If no setting for recording paper insertion wait or positioning timeintervals are made by one or more appropriate commands, a set of defaultvalues are provided which are then used. While similar to the previouslydiscussed fixed intervals, these period represent settings that areflexible and can be readjusted or set using appropriate host computercommands, at any time. At the same time, the more complicatedpositioning process needed for recording paper 170 is not normallyrequired for roll paper 171., and printing is executed directly fromdata analyzer 151 via printing controller 159.

A flowchart of the overall process steps executed by the control methodof the invention is illustrated in FIG. 5, in relation to printing oncut-sheet paper. In FIG. 5, print instructions are received in a step201, while print data is stored in RAM 61, substantially at the sametime. Initialization of the printing device mechanism is then executedin step 202, and plungers 15 and 16 are extended to open the printingsection and recording paper path in a step 203. In a step 204, whichtype of printing mode has been set or selected is detected. That is, itis determined which type of recording paper is to be used, eithercut-sheet or slip type paper on the one hand, or validation paper on theother. If slip mode is found to be selected in step 204 then theprinting process proceeds to a step 205 for typically used slip paper.Otherwise, if validation mode was selected in step 204 the processproceeds to a step 211 for validation paper.

When slip mode is selected, the output level of detector 6 is checked ina step 205 to determine whether or not recording paper has beenpositioned in the printing mechanism. If paper is positioned in theprinter, the optical beam used by the detector is blocked and the outputof detector 6 (see FIG. 4) changes accordingly. In the preferredembodiment, interruption of the optical light source generates an "OFF"condition or state in detector 6. Therefore, the printer waits in theinitial paper insertion (wait time) mode until detector 6 switches OFF.After detector 6 switches OFF, plunger 16 is retracted in a step 206 andform stop or stopper 7 is released and moved out of paper path 13, thusallowing the recording paper to be transported at the appropriate time.

Recording paper 170 is then transported in a step 207 to the printingsection where the leading edge of the recording paper is positionedrelative to the print head. Then, plunger 15 is retracted in a step 208,which closes the printing section and enables printing. At the same timethat the printer head is driven (printing) and recording paper is beingtransported (step 209), the point at which the end of slip or recordingpaper 170 passes the detector is determined in a step 210. The length ofpaper that has passed the detector is measured. When detector 6 changesto an "ON" state, that is, paper 170 is no longer present in the opticalpath of the detector, a predetermined length of paper is transportedthrough the printer until a predicted margin position is reached. Theamount or length of recording paper required for a desired minimumremaining printing margin, blank line, is stored at a preselectedaddress in memory in a step 215, here illustrated as RAM, and is used inconjunction with the measured length of paper passing detector 6 toperform a calculation in synchronization with transport of the recordingpaper to determine when the margin is reached and printing should end.The printing device print head is driven using input print data andrecording paper is transported in front of the print head until eitherthe end of the print data or the printing margin is reached (steps 216,217, 218). In a step 219, the recording paper is transported aprescribed amount and in a step 220 the printing operation isterminated.

In the same manner as in the slip mode, the printer device pauses invalidation mode until recording paper has been positioned in a step 211,and once it has been positioned, plunger 15 is retracted in a step 212.Stop 7 has a structure that does not require retraction of plunger 16since it does not regulate validation cards when inserted from the topor side of the printing mechanism, which also allows their easy removal.The structure of such as stop 7 is described in more detail elsewheresuch as in the co-pending U.S. Patent Application discussed above.Normally, control over positioning of the leading edge of the recordingpaper is not required in validation mode. Validation cards usedimensions that automatically align or position an appropriate printingregion of the card adjacent to the print head when the paper is insertedall the way to the bottom of notch 12, and transport is only executed bythe amount of the recording paper transport code contained in the printdata. In steps 213 and 214, delivery of print data to the print head andrecording paper transport are repeated or continued until detector 6switches ON. The remaining steps of the validation mode process are thesame as in those of the slip mode.

A flowchart for steps 205 and 211 of FIG. 5, as used in the recordingpaper positioning process of the invention, are described in furtherdetail in FIG. 2. As seen in FIG. 2, after a print instruction,initialization of the printing device mechanism is executed and waitinginterval timer is started in step 301 to measure the maximum time towait for insertion of recording paper. This is the activation of thesecond timer 152 discussed above.

The paper insertion detector is checked and its status confirmed in astep 302 to see if it has entered the OFF state, thus, indicatinginsertion of recording paper. Once the detector is checked in substep303 of step 302, an OFF state or condition for the detector is confirmedby checking its status again in a step 305, but after a delay time ofseveral milliseconds has been implemented in step 304. These delay timeand confirmation steps are used to prevent printer device mis-operationdue to transient detector noise or errors which briefly and incorrectlyindicate paper insertion. After the status of the detector is confirmedas OFF, i.e., insertion of recording paper is confirmed, another timeris activated or operated in a step 307 and reconfirmation of therecording paper is executed to establish that the recording paper hasbeen positioned in step 308. Step 308 details activation of the firsttimer (154) as described earlier, which allows for confirmation prior tocommencement of paper transport.

After recording paper positioning of is completed, control of theprinting device mechanism begins, and the open-close mechanism for therecording paper transport section is operated and moved to the closedposition in a step 309. The recording paper is then transported to aprinting position with a leading edge appropriately positioned in a step310 adjacent to the printing head. When the recording paper ispositioned in the desired printing position, the prescribed printingoperations are then executed in a step 311. When validation paper isused, the leading edge positioning process for the recording paper (seestep 310) is not executed.

When the waiting time exceeds the time as prescribed in step 301,printing is disabled and the appropriate warning message or indicationprovided, or other system action taken (step 312), to warn a printingdevice operator of an error in processing.

During operation of the above timers, a sufficient period of time isallocated for an operator to correctly position recording paper in theprescribed recording paper position of the printing mechanism. Thelength of this waiting period is conveniently set by preselectedcommands from the host computer.

An example of a command structure found useful for implementing thepresent invention is shown in FIG. 6. In FIG. 6, a command 401 forsetting a waiting interval or period of time for insertion of therecording paper and an appropriate pause or period of time beforerecording paper transport occurs or printing begins after insertion,i.e., recording paper positioning time, is shown. It should be notedthat a single command or different commands can be used to set these twointervals.

The command code structure of command 401 is preferably sub-divided intoat least three portions. The first portion of command 401 is "ESC f",which is a or command designation used to indicate the type of command.That is, what the remainder of the parameters in the command are beingprovided for or what operation they are associated with. This type ofcommand designation fits into a preselected or defined list of printercommands commonly used in the art, which are readily generated andinterpreted by host computers for operating printer mechanisms. Thoseskilled in the art will be familiar with working with and recognizingthis type of command designation or structure.

In the preferred embodiment, "ESC f" is defined or interpreted as acut-sheet paper waiting time setting command, and when this code is readby the command analyzer, it is interpreted as both a recording paperinsertion wait time and positioning time setting command, depending uponparameters provided with the remainder of the command.

A first parameter 402 is illustrated by the letter "m" and indicates adesired setting for the recording paper insertion wait time and, forexample, is typically set in increments of one minute each. Therefore,in this embodiment parameter 402 is set as a total of m minutes. Asecond parameter 403 is illustrated by the letter "n" and indicates adesired setting for the positioning wait interval from when insertion isdetected until transport of, or printing on, the recording paper begins.This time interval, for example, is set in increments of one-tenthsecond each. Therefore, in this embodiment, parameter 403 is set as atotal of n×0.1 seconds. In this embodiment, if m is set equal to 5 and nis set equal to 10, then the waiting times for cut-sheet paper insertionis 5 minutes and starting operation is 1 second, respectively. However,those skilled in the art will readily recognize that other timeintervals as best suited to particular application or hardware can beused within the teachings of the present invention. The intervalsindicated by these parameters are determined by criteria established inadvance by the calculation element, connected to or part of the CPU, andare measured using the appropriate timer. Preferred default values forthese parameters are m=0, infinite waiting time, and n=10.

The times indicated by the parameters or factors m and n in the waitingtime control command are interpreted or detected by data or commandanalyzer 151 and temporarily stored by memory controller 150 in RAM 62for later retrieval by the corresponding timers. These commandparameters are typically each configured using one byte of informationfor a two-byte command parameter length, but two or more bytes can beused as desired.

As described above, using the inventive configuration allows selectionof two or more recording paper wait time intervals (insertion andpositioning), thus facilitating establishment of wait intervalsaccording to operator experience and contributing to improved workefficiency. The ability to tailor wait times according to operatorexperience makes them extremely useful. Furthermore, since these timesor intervals are settable or selected by one or more host computercommands, they are also settable independently for each site; e.g., itcan be set according to the experience of register operators inlocations where there are many registers lined up in a row, such as in asupermarket.

Setting the minimum and maximum recording paper insertion wait times,allows the host computer to perform other operations without having towait indefinitely for insertion of the recording paper, even if notinserted, thus improving the operating efficiency of the computer whenmany POS terminals are controlled by one host computer. In addition,when insertion of the recording paper is late or delayed, warnings canbe generated and other processing performed while a response is pending.The recording paper insertion wait and recording paper positioning timescan both be set with the same command, thus offering greater conveniencein program control by a host computer.

Since the waiting time for cut-sheet paper can be controlled by acontrol command, even if a user enters the cut-sheet paper mode bymistake, if a waiting time for cut-sheet paper has been set, the modecan be escaped from after the set time elapses by sending a controlcommand from the host computer. No operator switch operation is requiredto re-start operation, and even if the cut-sheet paper is insertedincorrectly, if a waiting time for starting operation has been set, thepaper can be re-inserted correctly before the set time elapses.

What has been described is a new technique for controlling a printingdevice such as a POS-type printer which allows more efficient use ofwait intervals for paper insertion and transport.

The foregoing description of a preferred embodiment was presented forpurposes of illustration and description. It is not intended to beexhaustive nor to limit the invention to the precise form disclosed, andmany modifications and variations are possible in light of the aboveteaching. For example, other time intervals may be selected or the tiersimplemented using software generated timers or delay elements instead ofa timer built into the CPU. The embodiment was chosen and described tobest explain the principles of the invention and its practicalapplication to thereby enable others skilled in the art to best utilizethe invention in various embodiments and with various modifications asare suited to the particular use contemplated. It is intended that thescope of the invention be defined by the claims and their equivalents.

What is claimed is:
 1. A printing device comprising:printing means forprinting on a recording sheet; sheet transport means for moving therecording sheet adjacent and past said printing means; sheet detectionmeans for detecting the presence or absence of the recording sheetinserted into said printing transport means; an interface for receivingfrom a host computer a first predetermined time parameter representing adesired time duration for positioning the recording sheet in saidtransport means; time setting means for selecting and adjusting apredetermined first time interval in response to the first predeterminedtime parameter received from the host computer by said interface; andtiming means for initiating said sheet transport means to move therecording sheet to said printing means after said first predeterminedtime, selected and adjusted by said time setting means, has elapsedafter said sheet detection means detects the presence of the recordingsheet.
 2. The printing device of claim 1 further comprising:second timesetting means for variably setting a second time interval as a maximumwait time for recording paper insertion.
 3. The printing device of claim2 comprising warning means for producing an error signal if no recordingsheet is detected within said second time interval.
 4. The printingdevice of claim 2 wherein said timing means comprises at least a firstselectively programmable interval timer configured to count said firstinterval and a second timer configured to count said second interval. 5.The printing device of claim 2, wherein said interface receives from thehost computer various commands from a set of predefined commands,command data, print data, and other data strings therefrom, saidcommands comprising at least one command time setting command comprisingsaid first time parameter; wherein the printing device furthercomprises:analyzing means for interpreting received data and commands;memory means for reading and storing interpreted command data indicatingat least said first time interval as specified by said time settingcommand and providing said data to said timing means for measuring thetime period specified by stored command data; and control means foroperating said timing means for confirming detection of the recordingsheet and sheet positioning, and for initiating paper transport andprinting.
 6. The printing device of claim 5 wherein lengths of saidfirst and second intervals are set by a single time setting command. 7.The printing device of claim 5 wherein said memory means comprises:firstmemory means for reading command data defining said first time intervalas specified by the time setting command and storing it; second memorymeans for reading command data defining said second time interval asspecified by the time setting command and storing it; and furthercomprising:first timer means for measuring elapsed time based on thedata stored in the first memory means; second timer means for measuringelapsed time based on the data stored in the second memory means; firstactivation means for starting the second timer means and for confirmingwhether or not the recording sheet was inserted within the specifiedsecond time interval for recording sheet insertion; and secondactivation means for starting the first timer means.
 8. The printingdevice of claim 5 wherein:said time setting command comprises a two-bytelength command; said analyzing means is configured to interpret one byteof said two byte command as a command parameter indicating the length ofsaid second time interval for recording sheet insertion and the secondbyte of said two byte command as a command parameter indicating thelength of said first time interval for recording paper positioning; andsaid memory means stores the interpreted parameters.
 9. The printingdevice of claim 8 further comprising:calculation means for calculatingat least said first time interval based on stored parameters; andconfirmation means connected to the sheet detection means for checkingwhether or not recording sheet has been inserted within time intervalscalculated by the calculation means from the start of waiting forrecording sheet insertion.
 10. The printing device of claim 5, whereinsaid paper transport means has a transport section open-close mechanismto open and close a recording sheet transfer path and a recording sheettransport roller, and a recording sheet transport control means forconfirming the positioning of the recording sheet and then operating thetransport section open-close mechanism, holding the recording sheet sothat it can be transported, and driving the recording sheet transportroller.
 11. A method of controlling printing on cut-sheet type paper ina printing device, comprising the steps of:receiving from a hostcomputer a first predetermined time parameter representing a firstduration during which the printer will not print to allow for paperpositioning; receiving various predefined command data, print data, andother data strings from a host computer, at least one command being atime setting command for setting the length of said first duration;interpreting the received data and commands; interpreting the receiveddata and commands; storing interpreted command data indicating thelength of at least said first time interval as specified by a timesetting command; detecting by the printing device the presence orabsence of the paper inserted in the printing device; measuring by theprinting device a first time interval beginning with when the presenceof the paper is detected; measuring a first time period specified bystored command data, and initiating paper transport through a printingmechanism that prints a desired output on the paper when the first timeinterval exceeds the first duration, wherein said step of storingcomprises the steps of:storing command data defining the length of saidfirst time interval as specified by the time setting command in a firstmemory location; storing command data defining the length of said secondtime interval as specified by the time setting command in a secondmemory location; and further comprising the steps of:starting a timerfor measuring elapsed time for insertion of paper based on the datastored in the second memory location; detecting whether or not therecording paper is inserted during said second time interval; andstarting another timer for measuring elapsed time based on the datastored in the first memory location upon detecting paper.
 12. Theprinting device of claim 4 wherein said first programmable timer isconfigured to select a different timing interval in response to receiptof a host computer command.
 13. The printing device of claim 1 whereinsaid timing means comprises at least a first selectively programmableinterval timer configured to count said first interval, and furthercomprising:an interface connected to a host computer for receivingvarious commands therefrom, at least one command being a time settingcommand for setting the length of said first time interval; and memorymeans for storing data indicating said first time interval as specifiedby said time setting command and providing said data to said timingmeans for measuring the time period specified by the stored data.
 14. Aprinting device comprising:printing means for printing on a recordingsheet; sheet transport means for moving the recording sheet adjacent andpast said printing means; sheet detection means for detecting thepresence or absence of the recording sheet inserted into said printingtransport means; an interface for receiving from a host computer a firstpredetermined time parameter representing a desired time duration forpositioning the recording sheet in said transport means; time settingmeans for selecting and adjusting a predetermined first time interval inresponse to the first predetermined time parameter received from thehost computer by said interface; and timing means for initiating saidsheet transport means to move the recording sheet to said printing meansafter said first predetermined time selected and adjusted by said timesetting means, has elapsed after said sheet detection means detects thepresence of the recording sheet, wherein the recording sheet is manuallypositioned in said sheet transport means.